diff mbox

[v2,iproute2] get_rate: detect 32bit overflows

Message ID 1370274693.24311.154.camel@edumazet-glaptop
State Accepted, archived
Delegated to: stephen hemminger
Headers show

Commit Message

Eric Dumazet June 3, 2013, 3:51 p.m. UTC 
On Mon, 2013-06-03 at 16:36 +0100, Ben Hutchings wrote:

> Oops, I read this as being strtol() currently, not strtod().  Currently
> '1.5gbit' will work, but this change will break that.  So I think you
> need to keep bps as a double.

Arg

> Then here I think the check should be *rate != floor(bps), i.e. accept
> rounding down of a non-integer number of bytes but any other change is
> assumed to be overflow.

Thanks Ben, here is v4 then ;)

[PATCH v4] get_rate: detect 32bit overflows

Current rate limit is 34.359.738.360 bit per second, and
unfortunately 40Gbps links are above it.

overflows in get_rate() are currently not detected, and some
users are confused. Let's detect this and complain.

Note that some qdisc are ready to get extended range, but this will
need additional attributes and new iproute2

With help from Ben Hutchings

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 tc/tc_util.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)



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Comments

Ben Hutchings June 3, 2013, 4:31 p.m. UTC | #1 
On Mon, 2013-06-03 at 08:51 -0700, Eric Dumazet wrote:
> On Mon, 2013-06-03 at 16:36 +0100, Ben Hutchings wrote:
> 
> > Oops, I read this as being strtol() currently, not strtod().  Currently
> > '1.5gbit' will work, but this change will break that.  So I think you
> > need to keep bps as a double.
> 
> Arg
> 
> > Then here I think the check should be *rate != floor(bps), i.e. accept
> > rounding down of a non-integer number of bytes but any other change is
> > assumed to be overflow.
> 
> Thanks Ben, here is v4 then ;)
> 
> [PATCH v4] get_rate: detect 32bit overflows
> 
> Current rate limit is 34.359.738.360 bit per second, and
> unfortunately 40Gbps links are above it.
> 
> overflows in get_rate() are currently not detected, and some
> users are confused. Let's detect this and complain.
> 
> Note that some qdisc are ready to get extended range, but this will
> need additional attributes and new iproute2
> 
> With help from Ben Hutchings
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
[...]

Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>

Ben.
diff mbox

Patch

diff --git a/tc/tc_util.c b/tc/tc_util.c
index 8e62a01..8114c97 100644
--- a/tc/tc_util.c
+++ b/tc/tc_util.c
@@ -152,19 +152,23 @@  int get_rate(unsigned *rate, const char *str)
 	if (p == str)
 		return -1;
 
-	if (*p == '\0') {
-		*rate = bps / 8.;	/* assume bits/sec */
-		return 0;
-	}
-
 	for (s = suffixes; s->name; ++s) {
 		if (strcasecmp(s->name, p) == 0) {
-			*rate = (bps * s->scale) / 8.;
-			return 0;
+			bps *= s->scale;
+			p += strlen(p);
+			break;
 		}
 	}
 
-	return -1;
+	if (*p)
+		return -1; /* unknown suffix */
+
+	bps /= 8; /* -> bytes per second */
+	*rate = bps;
+	/* detect if an overflow happened */
+	if (*rate != floor(bps))
+		return -1;
+	return 0;
 }
 
 void print_rate(char *buf, int len, __u32 rate)